In recent years, an image forming apparatus which performs printing using decolorable toner has been developed. In such an apparatus, the decolorable toner and normal toner, which cannot be decolored, are used for different purposes.
In the image forming apparatus in which different types of toner are used in this manner, a predetermined test pattern will be printed on a sheet in order to check whether or not images formed by each toner type is being printed at a proper, intended position on the sheet.
However, in the image forming apparatus in which decolorable toner is used, when a test pattern is formed of both the decolorable toner and normal toner, there is a case in which a toner image formed using the decolorable toner becomes transparent due to heating associated with the fixing of the normal toner, which, generally, has a fixing temperature that is relatively high.
On the other hand, when fixing a test pattern to a sheet according to an appropriate fixing temperature of the decolorable toner, there is a case in which the fixing of the normal toner (which generally has a higher fixing temperature) is insufficient. In such a case, a transfer member of a transfer device will be contaminated due to the normal toner being separated from a sheet because of insufficient fixing, and as a result, a quality of an image formed on the sheet deteriorates.